Diarrhea with dehydration is a common illness among young children in the United States, accounting for over 10% of hospitalizations and 500 deaths per year among children under age five years. Diarrheal dehydration is preventable and treatable with the early and appropriate use of oral rehydration therapy (ORT), the administration of a balanced solution of glucose or stanch and electrolytes. Commercial oral rehydration solutions (ORS) are frequently recommended by health professionals and are widely available in pharmacies and some grocery stores. However, their high cost may serve as an economic barrier to their use by poor families, whose children are most likely to suffer fatal diarrheal dehydration. This proposal addresses this problem by evaluating the safety and effectiveness of homemade cereal--based ORS (C-ORS) in a controlled experimental fashion. C-ORS can be prepared from ingredients commonly found in the home, more safely than sugar-based ORS, and offers the additional advantage of reducing the volume, frequency, and duration of diarrhea. Currently there are no data available on the safety and effectiveness of homemade C-ORS in the U.S. This study will recruit children aged 4-36 months presenting in the Pediatric Emergency Department or Pediatric Primary Care Clinic of Boston City Hospital and Children's Hospital, Boston, with acute diarrhea. Patients will be randomly assigned to one of three treatment groups: Pedialyte, homemade C--ORS, or C-ORS prepared from a packet containing pre-measured cereal and electrolytes. Patients will be followed and data collected by study nurses who will visit the home daily until the illness resolves. Treatment failures, duration and frequency of diarrhea- serum electrolytes, and weight gain will constitute the main outcome variables. Samples of homemade C-ORS will also be obtained and assayed for sodium content. If the experimental C-ORS is found to be safe and effective, child health providers may choose it as a low-cost alternative to commercial ORS that, with proper supervision, may be recommended to families who may otherwise find the cost of ORT to be prohibitive.